Heat exchange apparatus



Feb. 28, 1933. E. B. FREEMAN 1,399,191

HEAT mxcnmem APPARATUS Filed Aug. 22, 1930 s Sheets-Sheet 1 Ely-Z fivaniar lI i'ineau' 6 3M.

Feb. 28, 1933. B FREEMAN 1 1,899,191

HEAT EXCHANGE APPARATUS Filed Aug. 22; 1950 3 Sheets-Sheet 2 t ll z'lnewa' 4 van or Patented Feb. 28,1933;

I U'Nireoi 'DFFICE nnnns'r n. FREEMAN; or NEWTON, M ssAoHUsE-r'rs; ASSIGNOR TO 3. 1'. srun-ravanr COMPANY, on HYDE mmx; Messiaen-mews, A coaronnrion or: missecnusn'r'rs HEAT EXCHANGE "APPARATUS,

. Application filed'A u gust 22, 1930.1 sw rm). 477,030.;

1 The present invention relates to heat exchange apparatus andfmore particularly/to a combined economizer and air heater for heating boththe feed 'water, for the boiler and theair delivered to theifurnaee.

The objectof the present invention is to provide a combined econonnzer and 'a rheat} er of simple, compactand efiicientconstruc- Hth this obje ct in view," the principal feature of the present invention comprises a plurality of double heat exchange elements,

each comprising tubes'arran'gedone within the other to form two conduits one foriwa- 'ter and the other for air. 'T-he'elements' are arranged in a flue preferably in staggered relation .to be heated by the hot flue gases.

Each set of airtubes is divided into a plurality of banks or rows connected" with suit able collecting chambers to permit parallel flow through the tubes ofeach bank, and a similar arrangement maybe provided to. permit parallel flow of Water through banks of water tubes. he invention may be C011". structed in either of two forms, namely,'w1th the water tubes inside the air tubes or w1th the .a-irtubes inside the waterytubes. The first-"form. of. the invention is advantageous in that it permits heating. of the air to. a higher temperature than the water, as'isf ordinarily required for maximum economy. On the other hand, the second form of the invention in which the water conduits are external to the air conduits, possesses'the advantage of superior heat transmission from the hot gasesto the water. {In any case, both the air :and water'tubes-are disposed across and through the entire flue to obtain maximum heat transfer with minimum loss of heat in the wastegases'to the atmosphere.

@ther features of the invention-consist of certain novel features of construction, combinations and arrangement of parts herein-. after described andparticularlydefined in the claims. p

o In the accompanying drawings; illustrating the invention in its preferred-forms, Fig. 1 is an end elevation partly in section of one .form of the invention employing internal waterfconduits and external air conduits;

I onalineA- l of Fig. 3; Fig.5 is an elevation partlyuinsection of another form of thein vention employing, internal air conduits and external water conduits; and Figr6 is a section on line 6-6 of Fig. 5.

The embodimentshowninFigs. 1 and 2 comprisesfia. flue 8 through which the hotgases passin anupward directiong A plurality :of. double, heat exchange elements 10 I are arranged horizontally in the flue. Each on air tube12 and aninner water tube l. The

heat exchangeyelement comprises an outer ends 160i the casing 8 comprises tube sheets for the air tubes 12,.each sheet having a plurality of holes into whichthe ends of the air v tubes are expanded. The elements are arranged in a pluralityof rows, shown as six rows, each of four elements. \The elements of adjacent rows are offset, asshown. in Fig. 1, ,p

to stagger the tubes in: the customary manner.

At one'end of the apparatus are an inlet col-. lecting chamber 18 communicating with some of the air tubes and an outlet collecting cham ber 20 communicating with the remainder of thefair tubes. At the opposite end of the apparatus is a single. collecting chamber 22 inletan'doutlet chambers are separated bya bafil'e'24v The chambers'18,20 and 22 are enclosedby an insulated casing 26. Air inlet and outlet ducts28 and '30 lead through the -80 communicating with allof the air tubes. The

casing tothe .chambers18 and 20 respectively. The'water "tubes '14extend beyond the ends of the air tubes and into the air collecting chambers. The water tubes are connectf nected in series for a 'singlefserpentine flow of water therethrough, by means ofhorizontalreturn bends 32 connecting adjacent tubes of the several rows, and inclined return bends 34 connecting end tubes of adjacent. rows.

Water inlet and outlet connections'36 and 38 are provided for the first and last tubes, re,-

spectively: The water tubes are supported on .horizontalangle irons 40 disposed below the return bends. I

Iiir tion, the hot flue gases flow up wardly through the flue over the external surfaces of the elements 10. The air and water admitted through their respective inlets flow horizontally across the flue, and in ,a general downward direction counter-current to the gases. By the baflle 24 the air heater is divided into two banks of tubes, each bank comprising three rows of four tubes each. Thus, the air flows from the inlet chamber 18 through the upper bank of twelve airtubes in parallel into the collecting chamber 22, and thence through the lower bank to the outlet chamber 20. The water courses back and forth from one tube to the next in the first row, and then through the tubes of the second row'in series, and so on, until it "reaches the outlet. The air, becauseof the largevolume which must bepassed through the apparatus, is preferably caused to'flow through only two banks, whereas the water because of its relatively small volume is passed at considerable velocity through all of the tubes in series. I

In operation, the air is heated to a high temperature by its passage through the outer conduits 12 which are heated by the flue gases. A portion ofthe heat extracted from theflue gases by the air is taken up by-the waterwhich flows through the inner conduits 14.

In this form of the invention, the water tubes are immediately accessible for repair or replacement. Access also be easily gained to any airtube bymerely removing its internal water tube,.an operation which is readily accomplished by disconnecting the return bends at opposite endsthe'reof. If actual removal of an airtube' is "required, it maybe necessary to takeout a pair oi'; the

*angle irons 40, and if this is done, care should be taken to block up the other'water t'ubes f the row temporarily.

The embodiment of the invention shown in-Figs. 3 and 4 is similar to that shown in thepreceding figures, except that provision is made for dividing the watertubes into a plurality of parallel flow sections or banks.

.The flue 8, the double elements 10, eachin eluding an external air tube 12 and an internal watertube14, the baflle 24 for dividing the air tubes into two banks, and the casing 26 are exactly similar to the corresponding parts previously described. Each row' of water tubes, however,is connected at Opposite ends into water collecting chambers or headers 42,

, by which the water is compelled to flow in into one header of the uppermost section and an outlet connection 48 leads from a header of the lowermost section. Headers of adjacent rows are connected by return bends 50. The headers are supported on side angle irons .52.

It will be seen that the air tubes are divided into two banks, eachconsisting of three rows of tubes,'through which the air flows in parallel,and' the water tubes are divided into six banks, each consisting of a single row of tubes; of twelve air tubes in the opposite direction 7 As in the previously described embodiment, access to the water tubes is simple and direct, it being only necessary to remove a cap 44 to reach any water tube. To repair an air tube, it is only necessary to remove the water headers for the correspondingrow,

The embodinient of the invention shown in Figs. Hand 6 issimilar to that shown in the preceding figures,in that it comprises a plurality of double heat exchange elements but differs in that the air is'carried by the inner conduits and the water in the annular space between the tubes. This embodiment oi the invention comprises the flue 60 having a plurality of rows of double heat exchange elements-62 arranged in staggered relation, as shown, in six rows of four each. Each element comprises an outer water tube 64 and an inner air tube 65. The outer or water tubes 64 are expandedinto horizontal headers 66 which are attached'to the end plates or tube sheets 68 of the flue. In the outside wall of each header are openings of at least as great a diameter as that of each water tube. Received in each opening is a plug 70 having a smallerconcentric opening through which the end ofthe air tube passes. The air tube is expanded into the'plug 70. The air tubes thus extend through the headers into collecting chambers 72 and 74 at one end and a collecting chamber 7 6 at the other end. The

chambers 72 and 74 which form air inlet and outlet chambers, respectively, are separated by abaflie78. Inlet and outlet ducts and 82 communicate with the chambers. A water inlet pipe 84 leads into the water header of the uppermost section and an outlet tube 86 leadsfrom the header of the lowermost section. Headers of adjacent rows are connected at the ends by return bends 88.

As in the other embodiments of the invention, the apparatus shown in Figs. 5 and '6 provides for a division of the heat exchange elements into a number of banks with a smaller number ofbanks for the air tubes than for'the watertubes' Each air bank' comprises three rows of air tubes and each water bank comprises asingle row of water tubes. r

All of the tubes of the apparatus are accessible for repair or replacement without the necessity for dismantling the entire apparat-us.- Thus, any air tube is immediately accessible by removing the outer casing, and any Water tube is easily made accessible by first removing the corresponding air tube and then the plug 70. 7

Having .thus described the invention, what is claimed is:

1. Heat exchange apparatus comprising a set of air tubes and a set of water tubes, the separate tubes of one set being contained within the separate tubes of the other set, a flue for hot Waste gases in which the tubes are disposed, collecting chambers to divide the set of air tubes into a plurality of banks, each including a number of parallel flow tubes, and flanged detachable returnbends for connecting water tubes. I

2. Heat exchange. apparatus comprising a set of air tubes and a setof water tubes, a flue for hot Waste gases in which the tubes are disposed, the separate tubes of one set being contained within the separate tubes'of the other set, collecting chambers to divide the set ofair tubes into a plurality of banks, each including a number of parallel flow tubes, the Water tubes projecting beyond the ends of the air tubes and into the collecting chambers, connecting means for the water tubes, and means for supporting the water tubes.

3. Heat exchange apparatus comprising a set of air tubes and a set, of water tubes, the separate tubes of one set being contained within the separate tubes of the other set, collectingchambers to divide the set of air tubes into a plurality of banks, eachincludinga number of parallel fiow tubes, the Water tubes projecting into thecollecting chambersbeyond the ends of the air tubes, individual return bends connecting the watertubes to cause series flow of water therethrough, and means in the collecting chambersfor supporting the water tubes.

4. Heat exchange apparatus comprising a plurality of double heat exchange elements, each consisting of an external air tube and an internal water tube projecting beyond the ends of the air tube, air collecting chambers at the ends of the air tubes, baflle means to divide the air tubes into a plurality of banks having provision for parallel flow of air through the tubes thereof, and individual return bends connecting the water tubes to cause series flow of Water therethrough.

5. Heat exchange apparatus comprising a plurality of double heat exchange elements,

each consisting of an external air tube and an internal water tube vprojecting beyond the ends of the air tube, air collecting chambers at the ends of the air tubes, baflle means to divide the air tubes into a plurality of. banks having provision for parallel flow of air through the tubes thereof, individual return bends connecting the water tubes to cause series flow of water therethrough, and means for supporting the water tubes.

are disposed and means for dividing each set into a plurality of banks comprising a number of tubes through which the fluid flows in parallel.

7. Heat exchange apparatus comprising a flue for hot waste gases, a set of air tubes and a set of water tubes, each of the separate tubes of one set being contained within aseparate tube of the other set, means for dividing the air tubes into a plurality of banks of parallel flow tubes, and means for dividing the water tubes into a plurality of banks, the air banks having a greater number of tubes than the water banks.

8. Heat exchange apparatus comprisinga flue for hot waste gases, a plurality of water tubes and a plurality ofair tubes, the separa-te water tubes being contained within and projecting beyond the ends of the air tubes, collecting chambers communicating with the air tubes, and headers connected with the Water tubes and disposed in the collecting chambers.

9. Heat exchange apparatus comprising a plurality of rows of double heat exchange elements, each consisting of an external air tube and aninternal water-tube projecting beyond the ends of the air tube, collecting chambers at the ends of the air tubes, a pair of headers for each row of water tubes, the

headers being disposed in the collecting chambers, and connections between headers of adjacent rows.

10/ Heatexchange apparatus comprising a plurality of rows of double heat exchange elements, each consisting of an external air tube andan internal Water tube projecting beyond the ends of the air tube, a plurality of collecting chambers to permit parallel flowofair through several rows of air tubes in parallel, a pair of headers for eachrow of water tubes to permit parallel water flow throughthe tubes of each row, and connections between headers of adjacent rows.

11. Heat exchange apparatus comprising a plurality of rows of double heat exchange elements, each consisting of an external air tube and an internal water tube projecting beyond the ends of the air tube, a plurality of collecting chambers to permit parallel flow of air through several rows of air tubes in parallel, a pair of headers for eachcrow ofwater tubes to permit parallel water flow through the tubes of each row, connections between headers of adjacent rows, and means for supporting the headers in the collecting chambers.

12. Heat exchange apparatus comprising a x plurality of water tubes, a plurality of air tubes, each air'tube being contained within a water tube, a flue for hot waste gases in which the tubes are disposed, a plurality of headers arranged at each end of the water tubes, each communicating with a plurality of tubes, and air collecting chambers each communicating with a plurality of air tubes.

13. Heat exchange apparatus comprising a set of air tubes and a set of water tubes, the separate air tubes being contained within the separate water tubes, and projecting beyond the ends of the water tubes, serially connected headers for the water tubes and collecting chambers for the air tubes to form a plurality of banks of parallel flow tubes for each set.

14. Heat exchange apparatus comprising a set of air tubes and a set of water tubes, the separate air tubes being contained within the separate water tubes, and projecting beyond the ends of the water tubes, headers for the water tubes and collecting chambers for the air tubes to forma plurality of banks of parallel flow tubes for each set, the banks 18. Heat exchange apparatus comprising a set of airtubes and a set of water tubes, a flue for hot gases, the separate tubes of one set being contained within the separate tubes of the other set, a collecting chamber for tubes of one set, headers and return bends located in the collecting chamber and connecting tubes of the other set.

19. Heat exchange apparatus comprising a setof air tubes and a set of water tubes, the separate tubes of one set being contained within the separate tubes of the other set, and collecting chambers for each set arranged at the ends of the tubes to provide for parallel flow of fluid through a number of tubes of each set, the collecting chambers of the one set being contained within the collecting chambers of the other set, and means for serially connecting the so contained collecting chambers to provide for series flow of fluid therebetween.

In witness whereof I have signed my name to this specification.

ERNEST B. FREEMAN.

of air tubes having a greater number of tubes than the banks of water tubes.

15; Heat exchange apparatus comprising a set of air tubes and a set of water tubes, separate air tubes being contained within the separate water tubes, and projecting beyond the ends thereof, headers for the water tubes, each having a wall provided with openings of a diameter substantially equal to that of the, water tubes, plugs for closing the openings in the headers, each plug having an opening through which the end of an air tube extends, and air collecting chambers communicating with the air tubes.

18. Heat exchange apparatus comprising a plurality of rows of double heat exchange elements, eachconsisting of an external water tube and an internal air tube, the air tubes projecting beyond the ends of the water tubes, a pair of headers for each row of water tubes, each header having at its outer wall openings opposed to the water tubes and of a diameter at least as great as that of the water tubes, plugs for closing the openings in the headers and having openings to receive the ends of the air tubes, the water tubes being expanded into the headers and the air tubes being expanded into the plugs, and collecting chambers for the air tubes to divide each set thereof into a plurality of banks, each bank comprising several rows of tubes through which the air flows in parallel. 17. Heat exchange apparatus comprising a set of air tubes and a set of water tubes, a flue for hot gases, the separate tubes of one set being contained within the separate tubes of the other set, a collecting chamber for tubes of one set, and flanged detachably return bends located in all of the chambers and connecting tubes of theother set. 

